1. Field of the Invention
The present invention relates to binders for magnetic recording media and, particularly, to compositions which show high dispersibility for finely-divided ferromagnetic powders and have excellent abrasion resistance.
2. Description of the Prior Art
Hitherto, as binders having the above described properties, cellulose derivatives, vinyl chloride-vinyl acetate copolymers, polyurethane resins, acrylic resins and copolymers thereof, vinylidene chloride polymers and copolymers, synthetic rubbers and polyesters, etc. have been used alone or as mixtures. Nitrocellulose which is a cellulose derivative disperses finely-divided ferromagnetic pigments quite well and imparts suitable magnetic tape characteristics when used as the binder for magnetic tapes. Nitrocellulose, however, has handling problems due to its character. Namely, it is capable of spontaneous combustion and it is very flammable. Further, copolymers composed mainly of vinyl chloride, for example, vinyl chloride-vinyl acetate copolymers, are not satisfactory in terms of their ability to disperse magnetic pigments, and other combinations of binders do not have sufficiently high dispersibility for magnetic materials and abrasion resistance.